This invention relates to cognitive radio based wireless communications of dynamic spectrum access networks, and in particular to a method of addressing zero-delay frequency switching for cognitive dynamic frequency hopping.
RF Spectrum scarcity, caused by costly spectrum access, becomes a major issue for deploying future wireless communication systems, according to the current spectrum allocation of regulatory organizations world wide. On the other hand, spectrum utilization measurements indicate that frequencies allocated in the licensed band are largely under-utilized. For example, measurement shows that only 5.2% of spectrum is in use in the US for the frequency bands below 3 GHz. Scarcity of spectrum licensing and under-utilization of licensed band motivate dynamic spectrum access that allows un-licensed wireless applications to operate in the licensed band while insuring no harmful interference to the incumbent users in the licensed band.
As an enabling technology for open spectrum access, cognitive radio is able to perform spectrum sensing, learning, and adapting to the RF environment so as to facilitate unlicensed radio operations and enhancement of spectrum reuse efficiency in intelligent ways. The key issues are RF spectrum sensing, learning, and adaptation, with objectives of guaranteeing incumbent service protection, and maintaining fair spectrum sharing and appropriate Quality-of-Service of cognitive radio systems.
The charter of IEEE 802.22, the Working Group on Wireless Regional Area Networks (“WRANs”), under the PAR approved by the IEEE-SA Standards Board is to develop a standard for a cognitive radio-based PHY/MAC/air-interface for use by license-exempt devices on a non-interfering basis in spectrum that is allocated to the TV Broadcast Service.
This invention provides Medium Access Control (MAC) methods for Cognitive Radio based dynamic access network systems, especially for IEEE 802.22 WRAN systems, addressing the key technical issues listed above.